1. Field of the Invention
The present invention relates to a vehicle lamp wherein a light source is fitted into a light-source fitting hole formed in a metal reflector disposed within a lamp chamber. More particularly, the invention relates to a vehicle lamp wherein a light source is fixed, by a plastic fixedly holding means, in the light-source fitting hole formed in a metal reflector.
2. Related Art
As shown in FIG. 7, a projection-type automobile headlamp as an example of the conventional lighting fixture of this type is provided with a light source unit integrating a substantially elliptic reflector 3 fitted with a bulb 4 as a light source, a cylindrical lens holder 5 and a projection convex lens 6 together within a lamp chamber defined by a lamp body 1 and a front cover 2. Reference numeral Sa denotes a shade for forming a clear cut line of a low-beam.
The bulb 4 is structurally formed by integrating a bulb body 4a as a light source with a plastic bulb socket 4b, and a focusing ring 4c formed with mating pawls 4c1in its peripheral edge portion is integrated with the outer periphery of the bulb socket 4b. On the other hand, a ring-like socket fixture 7 formed of synthetic resin is fixed with screws to the edge face of a cylindrical portion 3b forming a bulb fitting hole 3a in the reflector 3 and a mating groove 8 is formed so that the mating pawls 4c1on the side of the bulb socket 4b can be brought into engagement with the mating groove by bayonet coupling between the bulb fitting hole 3a and the socket fixture 7. The bulb 4 is made detachable from the bulb fitting hole 3a by turning the bulb 4 (the bulb socket 4b).
As the conventional projection-type headlamp of this type can be made compact to the extent that a smaller reflector is usable though a large quantity of light is available in comparison with a reflection-type headlamp using a parabolic reflector, the former is increasingly spotlighted and positively utilized for automobile headlamps.
However, because the reflector 3 in the aforesaid projection-type lamp is made of metal having high thermal conductivity (generally aluminum die-cast), it suffers from a problem that high temperature resulting from the generation of heat when the bulb 4 is lighted may subject to heat deformation any part of the plastic bulb socket 4b or plastic socket fixture 7 which is brought into contact with the reflector 3.